טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentRoee Diamant
SubjectTime Reversal MIMO Architecture for Very Shallow
Underwater Acoustic Communication
DepartmentDepartment of Electrical Engineering
Supervisor Professor Emeritus Feuer Arie
Full Thesis textFull thesis text - English Version


Abstract

Multi Input Multi Output (MIMO) scheme, combined with Time Reversal (TR) is a novel technique used for exploiting the time and spatial diversity characteristics of the underwater acoustic channel (UWAC). However, Inter Symbol Interferences (ISI) caused by the multipath phenomenon of the TR MIMO channel, limit the channel capacity over such channels. Two experiments were conducted during this work, showing that the channel is reciprocal and spatially un-correlated and thus suitable for TR MIMO techniques.

Our contribution includes a FIR model for the UWAC followed by an analysis of the TR MIMO system ISI level, resulting in a novel establishment of a reliability measure for the TR MIMO communication system performances. Several algorithms for the multidimensional ISI mitigation of the channel for phase modulation and orthogonal modulation communication systems have been developed and described in this work.

A shallow water experiment, showing a good fit between the estimated ISI and the analytic expressions, was conducted to check the proposed equalizers performances. The results show that the 2 X 2 TR MIMO channel capacity is 4 times larger than the non TR Signal Input Signal Output (SISO) channel capacity. The outcome of this work is a robust operational system for ISI mitigation using TR MIMO underwater acoustic communication tested in several sea trials.